Normalization of Emax and PVA
Part of the
Developments in Cardiovascular Medicine
book series (DICM, volume 177)
Analysis of the function of the whole ventricle is carried out conventionally by using the pressure-volume relation. However, the indexes derived from this relation do not represent the inherent properties of the myocardium; in other words, these indexes are not independent of the mass or geometrical features of the ventricle. For example, the value of Emax decreases with an increase in ventricular size even if myocardial contractility is assumed to be the same(1). If the elastic constants of the ventricle, such as Emax, were derived from the stress-strain system of the ventricular wall, they would be independent of the mass and shape of the ventricle, and represent local properties of the myocardium of the ventricular wall. However, there are presently no methods to measure stresses directly, and there are considerable discrepancies among the stress distributions in the ventricular wall calculated using various simplifying assumptions for the ventricular geometry and constitutive equations. Therefore, detailed stress-strain analyses are, at least clinically, of little practical utility.
KeywordsVentricular Wall Wall Stress Volumetric Strain Cavity Volume Ventricular Size
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